Production of artificial filaments, films, and like materials



Patented Feb. 21, 1939 UNITED STATES PATENT OFFICE PRODUCTION OF ARTIFICIAL FILAMENTS, FILMS, AND LIKE MATERIALS No Drawing. Original application July 21, 1930,

Serial No. 469,622. Divided and this application November 22, 1935, Serial No. 51,086. In Great Britain August 6, 1929 10 Claims.

This application, which is a divisional application from our application S. No. 469,622 filed July 21, 1930, relates to the production of artificial products, for example filaments, threads, ribbons, films and the like from solutions of cellulose derivatives, for example cellulose acetate, propionate, butyrate or other esters of cellulose or methyl, ethyl or benzyl cellulose or other cellulose ethers and is a continuation in part of U. S. application S. No. 402,785 filed October 26, 1929.

In U. S. application S. No. 402,785 filed October 26, 1929, we have described processes for the production of strong filaments, films, threads or other products by extruding solutions of cellulose derivatives into suitable coagulating baths and so conducting the process that the materials upon emergence from the bath are in a plastic state, or alternatively they are carried into a secondary bath which produces this plasticity. In effect this is brought about by having the filaments or other products in contact at some stage of their production with solutions of sol-. vents for the cellulose derivative of high concentration, for example, solutions containing solvents in a concentration of 25 to 65%. The products at the point of emergence may be so plastic that if brought together they would coalesce. In the said U. S. application three methods are described for achieving this object, namely (1) by incorporating in the spinning solutions solvents of higher boiling point than the non-solvent to be employed in the coagulating bath, (2) by incorporating solvents or swelling agents in the coagulating bath itself in high concentration,

and (3) by passing the formed products from a coagulating bath into a subsequent treatment bath containing the solvents. If desired any two or more of these three methods may be combined to produce their cumulative elfect. Preferably the solvents used are such that by reason of their innocuous properties they need not be washed out of the materials, and a small proportion thereof may be allowed to dry in. Moreover the solvents used are preferably relatively non-volatile or at least less volatile than lating bath or subsequent treatment bath is maintained at a temperature above atmospheric or so that the drying of the filaments, threads or other products after emergence from the coagulating bath or subsequent treatment bath is conducted under controlled conditions, for example in a controlled current of air or other drying medium, such control being preferably effected by passing the filaments and the like after emergence from the bath through a cell or chamber similar to that used in the dry spinning art.

The present invention relates to improvements in all such processes of wet spinning artificial products. The new process is of particular value in the case of coagulating baths or subsequent treatment baths which contain the solvent in a relatively high proportion.

According to the present invention while effecting coagulation of the filaments or other products from solutions of cellulose derivatives under such conditions that they are subjected to a strong softening action, or while treating the filaments or other products immediately subsequent to their production with strong solutions of solvents, salts, sugars or other solid polyhydric alcohols or other substances capable of reducing the solubility of the solvent in the nonsolvent medium are present in solution therein. The invention is of particular importance when the non-solvent medium employed in the coagulating bath or in the subsequent treatment bath is water, and in efiect the addition of the salts, sugars and other substances increases the osmotic pressure of the bath. I

The new invention may be carried into efiect in a number of ways. For example solutions of cellulose derivatives may be extruded into a coagulating bath consisting of a strong solution of a solvent for the cellulose derivative and containing the salts, sugars or other substances referred to. 0r again a solution of a cellulose derivative containing a solvent of higher boiling point than the non-solvent medium to be employed in the coagulating bath may be extruded into water or other non-solvent medium containing the salts or other substances. As a further modification filaments, threads, films or.

other products formed by coagulation in a suitable coagulating bath or formed by a dry spin- 1 media or which are capable of restoring or imparting lustre to partially delustred products are particularly valuable, see U. S. Patents Nos. 1,765,581 and 1,774,184.

The salts which are particularly suitable for the purpose of the present invention are salts which are insoluble in the solvent employed either in the spinning solution, in the coagulating bath or in the subsequent treatment bath and which are not hydrolysed by the water in the coagulating bath or subsequent treatment bath when aqueous baths are employed. ,In general therefore normal salts are employed which are compounds of strong bases with strong acids. The salts may be employed in any suitable concentration short of the concentration necessary to cause a separation of the solvent from the nonsolvent medium in the coagulating bath or subsequent treatment bath. In general therefore only comparatively low concentrations of salts are possible. For example in a 50% aqueous diacetonealcohol solution or aqueous ethyl lactate solution most salts are only soluble to a maximum extent of about 10%, and fact with percentages up to 10 very valuable results are obtained. Higher percentages may be employed if stable spinning is possible, but 15 to 20% represents about the maximum which may be used consistent with the presence, at some stage of the coagulation or subsequent treatment, of solvents in, high concentration. As examples of suitable salts for use according to the present invention the following may be instanced: Sodium sulphate, sodium chloride, sodium acetate, sodium nitrate and sodium phosphate, ammonium sulphate, ammonium chloride and ammonium nitrate and potassium sulphate, potassium chloride, potassiumnitrate, potassiumv acetate and potassiumphosphata, The best results appear to be obtained with sodium acetate, sodium chloride, ammonium sulphate, ammonium chloride, ammonium nitrate and potassium acetate in proportions of l, 2, 5 or 8 up to 10% on the weight of the bath., The salts used for the purpose of the present invention have little or no swelling action upon the cellulose derivative. A further class of bodies for use according to the present 'invention consists, as already indicated, in sugars and other solid polyhydric alcohols, for instance glucose, fructosepsucrose, xylose, mannitol, sorbitol, cellubiose, 'y-cellulose or other soluble degradation or depolymerisation products of cellulose.

As with the salts referred to above the sugars and other solid polyhydric alcohols may be used in coagulating. baths or in subsequent treatment baths in any concentration up to the point at which they would cause a separation of the solvent from the non-solvent medium employed therein. For instance when using a coagulating bath or subsequent treatment bath of aqueous diacetone alcohol in a 50-50% concentration an additionof about 20% of glucose will usually cause separation. Such a concentration of glucose is too high for this particular bath. The quantity of sugar or other polyhydric alcohol capable of causing separation of the bath into two layers will naturally vary with the particular solvent employed inithe bath, with the non-solvent employed therein and with therelative proportions. In no case however should the sugars and like substancesbe used in a concentration in excess of 30% of the weight of thebath, since higher concentrations unduly increase the viscosity of the bathand render spinning difiicult. Concentrations of 5, 10, 15 or 20% of glucose or like sugars yield very valuable results in the present processes.

It therefore appears that concentrations of salts of about 15-20% on the weight of the bath and concentrations of sugars of about 30% on the weight of the bath represent the outside limits for producing the valuable results of the present processes.

It has further been found that the use of the sugars or other polyhydric alcohols as described'above reduces or eliminates any tendency that the filaments or other products may have of sticking together after spinning, owing perhaps to local accumulation of the solvent on the yarn. v The sugars, salts or other agents capable of exerting an osmotic pressure or capable of reducing the solubility of the solvent in the nonsolvent employed in the coagulating or subsequent treatment bath may be employed in conjunction with any of the processes described in U. S. applications S. Nos. 402,785 filed October 26, 1929, and 437,423 filed March 20, 1930. As described in these U. S. applications by varying the concentrations of solvent employed either in the coagulating bath or in the subsequent treatment bath or in the spinning solution products having almost any. degree of lustre may be produced, for example from a very high lustre down to a medium lustre o'ra relatively low lustre, such as that of natural silk, or having an almost matt or non-lustrous appearance. Again the concentrationof salt, sugar or like substance employed also determines to some extent the lustre of the products produced, the lustre in general increasing with the concentration of salt, sugar or other added substance in the bath.

The solvents may be removed from the yarn or other products by simply Washing or by any other suitable process, and reference is made broadly to the description in U. S. application S. No. 402,785 filed October .26, 1929, for such treatments. The filaments, threads or the like may be wound in any suitable manner, as for example on bobbins or in a centrifugal spinning box or they may be dried and twisted and wound, as for example on cap spinning devices as described in U. S. application S. No. 437,423 filed March 20, 1930.

Products of relativelyhigh lustre produced according to the invention are delustrable or'partially delustrable by means of hot or boiling water or aqueous liquors or by means of moist steam. The lustre of products so delustred may howeverbe restored by treatment with salts or solvents as described in U. S. Patents'Nos. 1,774,- 1.84 and 1,808,098. By means of boiling aqueous liquors applied without tension products are obtainable having a very pleasing pearly'lustre and a soft handle. As opposed to the above products, products having a relatively low lustre obtainable by the present inventiondo'not appear tobe affected by any of the above agencies. The directly spun products or the delustred or relustred products obtained therefrom may be utilised in a variety of ways to obtain differential lustre effects. For examplea cellulose acetate yarn of relatively lowlustre may be woven, knitted or otherwise made up with the cellulose acetate yarn of relatively high lustre obtainable by the present process orby any other process, for instance the ordinary dry spinning process, to give aproduct'showing a differential lustre. I On subjecting such a productto a delustring agent the highly lustrous portion may be caused to lose its lustre wholly or in part and the portion of 'low'lustre may remain substantially unaffected. n

The following examples show the best methods known to us for carrying the invention into effect, but they are not to be considered as limiting the invention in any way:-.-

Examplel" V A 25% solution of celluloseacetate in acetone is spun through a jethaving orificesv of ;08 millimetre diameter into a spinning bath consisting of Parts by weight Diacetone a1cohol 45 Sodium acetate 8 Water 4'? The filaments are carried round afeed roller rotating at a peripheral speed of say 25 to 50 01 even up to 100 metres per minute, and the filaments are thereafter washed with water and wound on bobbins or collected in a centrifugal spinning box as required. Low filament deniers of 1.0 or less may thus be produced.

Example 2 The process is carried out as in Example 1 with the exception that the coagulating bath has the following composition:

Parts by weight Ethyl lactate 49 Sodium chloride 2 Water 49 The product has a somewhat lower lustre than that produced according to Example 1.

Example 3 A 25% solution of cellulose acetate in acetone is spun into a coagulating bath consisting of Parts by weight Diacetone alcohol 50-55 Glucose 12 /z7 Water 37 The spinning, washing and collecting is eifected as before.

Example 5 A 25% solution of cellulose acetate in acetone is spun into a bath containing:

Parts by weight Ethyl lactate 50 Glucose 5 Water 45 The lustre of the products is rather less than that obtained according to Example 1.

Example 6 A 25% solution of cellulose acetate in acetone is spun into a coagulating bath consisting of:-

' Parts by weight Diacetone alcoihol 25 Water 75 ute and is thence carried directly to a secondary bath consisting of: 7

Percent by weight and the remainder water. The thread is thereafter washed and reeled as desired.

What We claim and desire to secure by Letters Patent is:

1. In the manufacture of artificial filaments,

films and other products from solutions of organic derivatives of cellulose by wet spinning processes, the step of treating the products during such manufacture in a-liquid medium which contains an organic solvent for the organic derivative of cellulose in a concentration of at least 25% of the medium and a polyhydric alcohol which is normally solid.

2. In the manufacture of artificial filaments, films and other products from solutions of organic derivatives of cellulose by Wet spinning processes, the step of treating the product during such manufacture in an aqueous liquid medium which contains an organic solvent for the organic derivative of cellulose in a concentration of at least 25% of the medium and a sugar.

3. Process for the manufacture of artificial filaments, films and other products which comprises extruding a solution of an organic derivative of cellulose through a shaping device and coagulating the shaped solution in a coagulating medium which contains an organic solvent for the organic derivative of cellulose in a concentration of at least 25% of the medium and a polyhydric alcohol which is normally solid.

4. Process for the manufacture of artificial filaments, films and other products which comprises extruding a solution of an organic derivative of cellulose through a shaping device, coagulating the shaped solution in an aqueous coagulating medium which contains an organic solvent for the organic derivative of cellulose in a concentration of at least 25% of the medium and a polyhydric alcohol which is normally solid, and subjecting the materials to a stretching operation while they are travelling through the coagulating medium.

5. Process for the manufacture of artificial filaments, films and other products which comprises extruding a solution of cellulose acetate through a shaping device and coagulating the shaped solution in an aqueous coagulating medium which contains an organic solvent for the cellulose acetate in a concentration of at least 25% of the medium and a polyhydric alcohol which is normally solid.

6. Process for the manufacture of artificial filaments, films and other products which comprises extruding a solution of cellulose acetate through a shaping device, coagulating the shaped solution in an aqueous coagulating medium which contains an organic solvent for the cellulose acetate in a concentration of at least 45% of the medium and a sugar, and subjecting the materials to a stretching operation while they are in a softened condition.

'7. Process for the manufacture of artificial filaments, films and other products which comprises extruding a solution of an organic derivative of cellulose through a shaping device, coagulating the shaped solution in an aqueous coagulating The thread is carried round a feed roller rotat-- ing at a peripheral speed of 40-50 metres per minwhich c'ontains an organic solvent for the organic derivative of cellulose which is less volatile than water, in a concentra't'iohof at least 45% of the medium, and a polyhydric alcohol which is normally solid, and subjecting the materials to a stretching operation while they are traveling through the coagulating medium.

8 Process for the manufacture of artificial filaments, films and other products which comprises extruding a solution of cellulose acetate through a shaping device, coagulatingthe shaped solution in an aqueous coagulating medium which contains a sugar in a concentration of 530% of the medium and an organic solvent for the cellulose acetate which is less volatile than water in a concentration of at least 45% of the medium, and subjecting the materials to a stretching operation while they are in a softened condition. v

9. Process for the manufacture of artificial filaments, films and other products which comprises extruding a solution of cellulose acetate through alums a shaping "device, coagulating the shaped solution in an aqueous coagulating medium which contains a "sugar in a concentration of 530% of the medium and ethyl lactate in a concentration of at least 25% or the medium, and subjecting the materials to a stretching operation while they are in a softened condition.

10. Process for the manufacture of artificial filaments, 'films and other products which comprises extruding a solution of cellulose acetate through a suitable shaping device, coagulating the shaped solution in an aqueous coagulating medium which contains a sugar in a concentration of 5-30% of the medium and ethyl lactate iii a concentration of at least 45% of the medium, and subjecting the materials to a stretching operation while they are travelling through the coagulating medium.

W LLI M A EfiiAliD R C PERCY FREDERICK COMBE SOWTER.

CERTIFICATE OF CORRECTION. Patent No, 2,1LL7,6LL2. February 21, 1939.

WILLIAM ALEXANDER DICKIE, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, first column, line 61, for "50- 50%" read 50-55%; and that the said Letters Patent should be read with this correctiontherein that the same may conform to the record of n the case in the Patent Office. I Signed and sealed this 11th day of April, A, D, 19 9.

Henry Van Arsdale (Seal) Acting Commissioner of Patents, 

